The present invention relates to a device for continuously mixing liquid products and/or pulverulent products.
Devices for mixing liquid products and/or pulverulent products are well known. In particular, they are described in French Patent No. 2 414 952 and its Certificate of Addition No. 2 443 277.
In its most simple form, shown for example in accompanying FIG. 1, such a device comprises an outer tubular casing 10 presenting an open end 12 for the discharge of the mixture and an open end 14 for the infeed of one of the products to be mixed. Reference 16 designates the system of infeed of the second product to be mixed. Inside the tubular casing 10 is located a rotating mixer member 18 which is in the form of a helix extending over a large part of the length of the tubular casing. The mixer member 18 is driven in rotation about axis xxe2x80x2,xxe2x80x2 of the tubular casing by a motor 20. Rotation of the helix 18 ensures both the mixture of the liquid and/or pulverulent products, and the entrainment of the mixture produced towards the discharge end 12.
When this type of mixer is used for products which are hygroscopic, adhesive, clogging or hardening, caking occurs inside the helix 18 upon encountering the products to be mixed. This effect of caking on the helix 18 alters the efficiency of the mixture by the helix 18 and can therefore entrain to the outlet of the mixer a finished product which is non-homogeneous or even lumpy.
Document U.S. Pat. No. 3,381,801 describes a tubular device for conveying pulverized products. This device comprises a spiral element and an axial tubular bar mounted inside the spiral. One end of the bar is fast with the tubular casing of the device and this bar extends over the whole length of the path of the pulverized products in order to limit the free volume for the pulverized product. Such a device can in no way solve the problem raised.
It is an object of the present invention to provide a device for mixing liquid products and/or pulverized products which avoids the risks of the mixture caking on the helix of the mixer, without decreasing the efficiency of the mixer nor reducing its flowrate.
To attain that object, the device according to the invention for continuously mixing liquid products and/or pulverized products, comprising at least one outer tubular casing, means for supplying products to be mixed disposed at a first end of the tubular casing, the second end of the tubular casing being open for the discharge of the mixture, a mixer member having the form of a helix of inner diameter D disposed inside the tubular casing, and means for rotating the mixer member about the axis of said tubular casing, further comprises an elongated piece closed at its two ends, of diameter d, with d less than D, and of length l less than the length L of the mixer member, said piece being mounted radially free inside the mixer member and being radially free with respect to said outer tubular casing to form an imbalance, and means for axially holding said cylindrical piece inside the mixer member.
It will be understood that the cylindrical elongated piece which is mounted free inside the turn forming mixer member, i.e. without any mechanical link between the elongated piece and the mixer, constitutes the equivalent of an imbalance. Due to the rotation of the helix and the absence of mechanical link, the cylindrical piece hits the inner face of the turns of the helix, preventing caking of the mixture or causing any caking to be detached from the helix. In addition, it will be understood that the cylindrical piece is immobilized in translation, on the one hand, by the holding means disposed at the discharge end of the mixer and, on the other hand, by the effect of the products to be mixed entrained by the mixer member.
It goes without saying that, depending on the nature of the products to be mixed, the elongated piece mounted free in the mixer member will have different dimensions and suitable weights.
The ends of the elongated piece are preferably shaped.